CROSS-LAMINATED TIMBER (CLT) PRODUCTION
The Cross-Laminated Timber Team’s purpose is to offer an alternative sustainable material and to decarbonise the construction industry. The team is currently focused on different structural tests to investigate timber material properties and the effects of adhesives under different conditions. Due to the anisotropic nature of timber - strength along the grain, each configuration and test must take into account load direction and purpose of application.
CROSS-LAMINATED TIMBER (CLT) INTRODUCTION
Cross-laminated timber (CLT) is produced through a process of layering and bonding multiple layers of timber using an adhesive at perpendicular angles. Engineering and optimising the timber product yields a material superior in properties of strength, thermal and sound insulation, and fire resistance. The sustainable building material reduces carbon emissions while enabling faster construction and enhanced architectural flexibility.
TIMBER & ADHESIVE SELECTION
A crucial part of the CLT design process involves the selection of timber and adhesives to be used in the design. In terms fo the timber selection, the main considerations as to what makes a ‘good’ timber is the density, abundance of supply locally as well as the costs associated with purchasing and working the wood.
Selection of adhesives for the design focuses on the different interactions between the adhesives and wood that elicit mechanical property changes with other side factors such as toxicity, foaming and local supply all thoroughly considered.
CURRENT STRUCTURAL TESTING
Once the timber is adjusted to the correct moisture content in an enviro chamber, the material properties of timber are first analysed by performing bending and compression tests on a single layer. Specifically, the 3-point bending test is conducted to provide the flexural strength and modulus of elasticity in bending while allowing the team to calculate the shear strength without a separate shear test. The compression test will reveal how well the timber performs under compressive stress. Testing of adhesives will follow a similar process to timber properties however utilising 2-layer samples.
FUTURE TESTING
Due to the nature of timber grains, its properties will change depending on the direction of load. As such, adjustments must be made to structural tests based on the application such as for flooring or shear walls. Samples produced by the team will be tested extensively under different conditions and standards to meet requirements. Current planned tests are for load perpendicular to the plane however there are plans to test this parallel to the plane. These tests will provide information on flexural strength, buckling, both horizontal and vertical shear, and compressive stress. In addition, there are plans to test for vibration resistance and de-lamination rates for each sample.